NASA astronomers have discovered that supernovas may not always destroy stars, and in some instances can leave behind zombie stars, “battered and bruised” white dwarf remnants.
Supernovas, which are the most powerful explosions in the universe, expel most of a star’s matter into space, obliterating the white dwarf that exists before the nova, as The Inquisitr has noted. Astronomers using the Hubble Space telescope believe they have discovered a star system, however, in which a rare Type Iax supernova has left behind a “zombie” star remnant. In these types of supernovae, which have only been observed 30 times by astronomers, less of a star’s mass is ejected. As The Washington Post reports, in the case of supernova SN 2012Z, the white dwarf that should have been destroyed may have risen from its cosmic grave, in a manner of speaking.
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SN 2012Z, which was a weak supernova, could possibly have been caused by a white dwarf interacting with a companion star, astronomers say. They believe that the white dwarf passed hydrogen and helium to its companion star, until the companion effectively engulfed it. The combined star ejected its outer layers, leaving only the white dwarf and a helium core. As the white dwarf pulled mass from the helium core, it triggered a small supernova.
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“Usually during a supernova, a white dwarf would just be totally gone,” Curtis McCully, who co-authored a study on SN 2012Z set to appear in Nature, pointed out. “In this case, the white dwarf is still just a white dwarf. How the companion star changed, if it survived the explosion, is another question.”
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Researchers will have to wait until late 2015 for the light from the supernova to fade, Space.com reports. After that, they hope to get another look at the system, to see what remains of the white dwarf and its companion star. According to Saurabh Jha, an astronomer at Rutgers University in Piscataway, New Jersey who co-authored the study, there are two possibilities. Researchers could see no remnant star, which would be the case if the progenitor was in fact a massive star before the supernova. The other possibility is that a helium star will remain, “but it will have changed due to the explosion.”
Jha also pointed out that researchers “hope to see the remnant zombie star” in 2015.
[Image via Time]